Daniel dbawbaugh



(No lModel.) Y l DDRAWBAUGH., i

VIEHLEPHOII TRANSMITTER. I

Patented Mm. 25, 1884.

mm M22@ l al@ A? ATTORNEYQ'S; i

PATENT OFFICE,

DANIEL DRAWBAUGH, or nennLYfs MILL, PENNSYLVANIA, AssIeNon' To THE PEOPLE S TELEPHONE TELEPHONE-T COMPANY, OF NEW YORK.

RANSMITTER.

SPECIFICATION forming part of Letters Patent No. 295,741, dated March 25, 1884.

` Application filed November 152, 1883. (No modela .To @ZZ whom t 11mg; concern/ Be it known that l', DANIEL DRAWBAUGH, of Eberlys Mill, Cumberland county, Penn- Sylvania, have invented a nen7 and` useful Improvement in Telephone Transmitters, of which the following is a speciiication.

The invention relates` more particularly to the construction and 'arrangement of electrodes, as herein set forth,.the said electrodes consisting of a fixed piece of carbon or other suitable material rigidly attached` to a support, and having an inclined face; and, second, of a cylinder of carbon or other suitable material sustained by another support and resting upon the inclined face of the iiXed electrode. Either one or both of said supports may be a diaphragm or sound-receiving surface;

In the accompanying drawings, Figure l is a frontview of the instrument withthe cover and outer diaphragm removed, the cylindrical electrode being shown in place. Fig. 2 is a verticalsection on the line x x of Fig. 1. Fig. 3 is a partial section of the cylindrical electrode. Fig. 4 is a rear view ofthe outer diaphragm. i

Similar letters ot' reference indicate like parts. I

A is the back board of the instrument.

B is the containing-case;

C and D are diaphragms arranged, respectively, upon the front and rear sides Vof theinstrument.

E and F are covers containing central oriiices to allow of access of sound-waves to the diaphragms. y

It will be seen that in the form of instrument here shown I employ two diaphragms. Against one of these, C, the sound-waves directly impinge, while said 'waves meet the other diaphragm, D, afterareflection from the back board, A. To, the rear diaphragm, D, and substantially at/the center thereof, is secured a metal bracket, G, containing an electrode, H, the said electrode being inclined or having air upper inclined surface, substani tially as shown in the drawings. I have ob tained good results by making this electrode of carbon. `Resting upon the upper inclined 5o face of the electrode His the cylindrical electrode I. This electrode may be formed wholly of a block of carbon. I have found, however, the particular construction shown in Fig. 3 to be preferable in practice. As there represented,` the said electrode consists of a 5 5 tube of carbon, J, filled with powdered car` bon K, the ends being closed by pieces of pay, per or other insulating material cemented or otherwise secured in place. Entering the electrode I, and insulated from the tube J by a 6o sleeve of insulating material, Y, and having a T end embedded in the powder contained in said electrode, is a metal rod or electrode, V L. The end of the rod L is loosely received in a socket-tube, M, which socket-tube is suit- `6 5 `ably secured at the center ofthe diaphragm C.

In order to hold said socket-tube more iirmly in place, I may apply to the rear side of said diaphragm a block of wood, N, in order to increase the thickness of the diaphragm; but I 7o do 'not limit myself to this or any other particular means of securing the diaphragm G and socket-tube M together, inasmuch as variousmethods of connecting these parts will readily ,suggest themselves. M is of metal, and to it one of the circuitwires is electrically connected. The circuits in the instrument proceed as follows: from the battery to the bindingposts l, by the wire a to the primary of the 8o induction-coil O, and thence by the wire b to the metal bracket G, to the electrode I-I, to the electrode I, to the socket-tube M, and thence, by the wire c on the rear of the diaphragm O, Fig. 4, to the metal contact-piece 8 5 I), secured upon said diaphragm. When the diaphragm@ is in place, the circuit continues from the contact-piece P to a spring contactpiece, Q, secured to the case, and thence bya Wire, D, to a at metal contact-piece, R. A 9o spring contact-piece, S, is secured inside the box of the instrument, and has one end, T, bent at right angles to pass downihrough an opening in the bottom of said box, the contact-piece S then overlapping the contactl piece R. The circuit continues from the contact-piece R to the contact-piece S, when the same are in contact, and iinally proceeds from said contact-piece S by a wire, e, to the binding-post'2, and thence back to the battery. Ico

The socket-tube 7,5

The secondary of the induction-coil proceeds by wiresf to the line binding-posts 3 and 4. From said wires f eXtend branch wires g g to the binding-posts 5 and 6, to which bindingpost a receiving-instrument may be connected.

To the back board of the instrument7 and below the arm T of the contact-piece S, is secured an arm, U, to receive the ring of the receiving-instrument when the same is not in use, the said ring then lifting the piece S out of contact with the piece It, and so breaking the primary circuit oi' the instrument.

In the form of telephone here shown,where two diaphragms are employed, I interpose between the back board and the box or case of the instrument blocks V, so as to leave an air-space between the rear diaphragm and the back board, A, into which sound-waves may enter. I nd it preferable to secure the induction-coil O directly to the back board, A, and to make an opening in the diaphragm G to receive it. In order to prevent displacement of the induction-coil, I provide a bar, IV, and to prevent the electrode from becoming displaced I arrange above it an arm, X, the under side of which arm is covered with paper or other insulating material.

The operation of the instrument is as follows: The sound-waves produced by the voice impinge directly upon diaphragm C, and after a reilection from the back board,A, also upon the diaphragm D. These diaphragms are therefore both set in vibration, and communicate their motions to the electrodes H I, thus causing the same to produce modifications in the current passing through them.

I do not limit myself to a telephone containing the electrodes, as described, in combination with two diaphragms, inasmuch as I may suppress the diaphragm B and back cover, F, altogether, and cause the metal bracket G and electrode I-I to be sustained by the back board, A, or any other suitable support.

I claim as my invention- 1. An electrode for telephone-transmitters, composed of an envelope of carbon or other conductor containing a mass or body of finelydivided conducting material, substantially as described.

2. An electrode for telephone-transmitters, consisting of an envelope of carbon or other similar conducting material containing a mass of iinely-divided conducting material, and an electrode penetrating the envelope and insulatedv therefrom, and embedded in the iinelydivided material, substantially as described.

3. An electrode for telephone-transmitters, composed of a tubular shell of carbon or other similar conducting material, closed at both ends, and containing a mass of finely-divided conducting material, substantially as described.

4. An electrode for telephone-transmitters,

composed of a tubular shell of carbon or similar conducting material, closed at both ends, and containing a mass of iinely-divided conducting material, in combination with an electrode passing through said shell and insulated therefrom, and embedded in the finely-divided conductor, substantially as described.

5. In a telephone, a diaphragm or soundreceiving surface, an electrode having an inclined upper surface, asecoud electrode consisting of a shell of conducting material containing iinely-divided conducting material, and a third electrode embedded in said finelydivided material and insulated from the shell, and having its end loosely connected to the diaphragm, substantially as described.

6. In a telephone, a diaphragm, an electrode of cylindrical form loosely connected to said diaphragm, and a iixed electrode having an inclined upper surface, the loose electrode resting upon said surface by gravity, substantially as described. y

7. The combination of the diaphragm C, socket-tube M` rod-electrode I, cylindrical electrode J K,`inclined fixed electrode H, and a support for said last-mentioned electrode, substantially as described. 8. In a telephone, a diaphragm, a support, and three electrodes, one electrode having an inclined upper surface and rigidly attached to the support, the second electrode resting upon the inclined electrode by gravity, and containing conducting material in a finely-divided state, and the third electrode having one end embedded in said finely-divided material and the other end loosely connected to the diaphragm, substantially as described.

9. Iifa telephone, two diaphragms and three electrodes, one electrode having an inclined upper surface and rigidly attached to one of the diaphragms, the second electrode resting upon the inclined electrode by gravity, and

containing conducting material in a Iinely-di-- vided state, and the third electrode having one end embedded in said iinely-divided material and the other end loosely connected to the other diaphragm, substantially as de IIO 

